Regenerating catalyst with tangential introduction and circumferential swirl in a fluidized bed

ABSTRACT

A regenerator design and method of operation is described which relies upon a segmented regeneration gas distributor grid to vary regeneration gas flow rate upwardly through the bed of catalyst thereabove. An expanding annular section formed by a curved vertically extending baffle positioned adjacent and downstream of the catalyst tangential inlet implements the catalyst circumferential swirl type operation within the regenerator.

United States Patent Fagan et al. Sept. 9, 1975 [54] REGENERATINGCATALYST WITH 2,794,841 6/1957 Hay et al. 208/162 TANGENTIAL AND3,394,076 7/1968 Bunn, .11. et al. 252/417 3,647,714 3/1972 White252/417 CIRCUMFERENTIAL SWIRL IN A 3,806,324 4/1974 Maclean et a].252/417 FLUIDIZED BED 3,821,103 6/1974 Owen et al 252/417 BaffleInventors: Frank N. Fagan, Furlong, Pa.; Joe

E. Penick, Chappaqua, N.Y.; Klaus W. Schatz, Cherry Hill, NJ.

Mobil Oil Corporation, New York, N.Y.

Filed Sept. 10, 1973 Appl. No.: 395,816

Assignee:

U.S. Cl 252/417; 23/288 B; 23/288 S; 208/164 Int. Cl. B01j 11/68; ClOg11/18 Field of Search 252/417; 208/164; 23/288 B, 288 S References CitedUNITED STATES PATENTS Gerhold 252/417 Primary ExaminerWinston A. DouglasAssistant Examiner-P. E. Konopka Attorney, Agent, or Firm-Charles A.Huggett; Carl D. Famsworth A regenerator design and method of operationis described which relies upon a segmented regeneration gas distributorgrid to vary regeneration gas flow rate upwardly through the bed ofcatalyst thereabove. An expanding annular section formed by a curvedvertically extending baffle positioned adjacent and downstream of thecatalyst tangential inlet implements the catalyst circumferential swirltype operation within the regenerator.

ABSTRACT 4 Claims, 3 Drawing Figures PATENTED 91975 3.904548 sum 1 BF 2FIGURE 1 FIGURE IL PATENTED SEP 91975 3.904, 548

SHEET 2 OF 2 FIGUREDI REGENERATING CATALYST WITH TANGENTIAL INTRODUCTIONAND CIRCUMFERENTIAL SWIRL IN A FLUIDIZED BED BACKGROUND OF THE INVENTIONThe technology of contacting finely divided solid particles withgasiform material to obtain conversion with the solid particles,extraction of the particles or the removal of deposited materialstherefrom wherein the solids are maintained in a fluid phase conditionare plagued with problems associated with obtaining a relatively uniformcontact between supplied gasiform material and solid particle material.Thus in large fluid bed operations employed for the regeneration ofcatalyst particles, means for obtaining a desired distribution ofregeneration gas throughout the regenerator cross section and catalystbed to obtain a desired removal of carbonaceous deposits has been asource of constant investigation to obtain improved results. Theproblems of regenerating catalyst have been aggravated with thedevelopment of more active and selective cracking catalysts; that is,cracking catalysts that are more selective at high temperatures and ofhigh or low coke producing characteristics. Furthermore, to takeadvantage of the catalyst potential for converting hydrocarbons, it isimportant to obtain a substantially complete uniform removal ofdeposited carbonaceous material before return thereof at an elevatedhydrocarbon conversion temperature to the hydrocarbon conversion step.The present invention is concerned with the method and apparatus fordistributing gasiform material to the bottom portion of a fluid bed offinely divided solid particle material to obtain regeneration thereof.

SUMMARY OF THE INVENTION The present invention relates to the method andapparatus for contacting finely divided solid particle material with agasiform material under selected operating conditions. In one aspect,the present invention is concerned with a method for improving therecovery and separation of compounds adsorbed on the catalyst duringconversion of hydrocarbons. In another aspect the invention is concernedwith the regeneration of finely divided solid catalyst particles in aswirl type catalyst regeneration zone to obtain removal of carbonaceousdeposits by burning in the presence of an oxygen containing gasiformmaterial. In the swirl type catalyst regeneration system of the presentinvention, the solid catalyst particles are regenerated in a fluidcatalyst bed operation varying in bed density and supplied withregeneration gas in the lower portion thereof by a plurality ofradiating distributing grids or segments individually controlled withrespect to the volume of regenerating gas passed through any givensegment.

The plurality of horizontally radiating distributing grids positioned inthe lower portion of the regeneration zone extend outwardly from acentral vertically extending regeneration gas inlet conduit projectingupwardly into the bottom portion of the regeneration vessel. Eachradiating grid segment is provided with a horizontally disposedregeneration gas distributing conduit from which a plurality of spacedapart distributing pipes extend at a right angle thereto to fill atriangular segment of the cross-sectional area of the regenerationvessel. In the arrangement herein provided and discussed, thecross-sectional area of the vessel is separated into six relativelyequal triangular segments and each segment is provided with its owndistributing grid with fluid flow control means as herein explained. Inthis arrangement, each grid segment is provided with a regenerating gassupply support conduit extending upwardly and outwardly from the mainvertically disposed regeneration gas inlet conduit to the horizontallydisposed distributing conduit and is in open communication therebetweento permit the flow of regeneration gas therethrough. Thus the supply ofregeneration gas to the outer portion of each distributing segment isaugmented by the open end support conduit above identified. Theregeneration gas distributing pipes closedat the outer end thereof areprovided with a plurality of downwardly extending nozzles or orificemeans throughout the length of the pipe on the bottom side thereofthrough which the regeneration gas is passed under selected pressuredrop conditions restricted to within the range of 0.4 to 1.2 psi tominimize catalyst attrition and turbulence before flow upwardly throughthe bed of solids thereabove under fluidizing conditions.

In the arranement of the present invention, each separate horizontalfluid distributing and supply conduit and each support conduitcommunicating therewith is I provided with simple plate or butterflyvalve means at the inlet of each conduit projecting from the substantialvertical gas inlet conduit projecting upwardly into the bottom portionof the vessel. The vertically aligned valve means associated with eachdistributing gas segment are controlled by a vertically extending rodmeans associated with the valves which are coupled to control meansextending through the wall of the vertical gas feed conduit external tothe vessel. Thus the valve means at each inlet may be simple butterflyvalves or plates connected to the vertical rods and positioned withrespect to the radiating conduit inlets to permit altering the flow ofregeneration gas therethrough by partially or completely covering theinlet. Complete coverage of the inlet is not necessary. Also, flow ofregeneration gas through'distributing pipes provided with nozzle ororifice means is controlled by restricting the orifice size and in somecases limiting the number of available orifices.

In the regeneration of solid particle material, such as finely dividedcatalyst particles, it is known that temperatures within the range of800 to l400F. may be employed; it being preferred to regenerate catalystfor cracking operations at temperatures in excess of l F. and usually attemperatures of at least 1300F. Furthermore, the regeneration operatingpressure may be about atmospheric or considerably higher and up to about100 or 200 psig. The regeneration of catalyst for cracking operations isoften accomplished at atmospheric pressures or slightly higher pressuresup to about 50 or 100 psig. In such an operation the velocity of thegasiform material passed upwardly through the fluid bed of solids mayvary over a considerable range and is controlled to obtain a desireddispersion within the range of dense to a less dense suspended phase ofsolids in the upflowing gasiform material. Thus depending on the densityof the fluid bed of solids desired in the regeneration zone, thegasiform material will be introduced to provide a velocity within therange of 0.5 up to 5, 10 or higher feet per second. More usually thevelocity of the gasiform material such as oxygen containing regenerationgas used to remove carbonaceous deposits by burning is sufficient tomaintain the solid particle materials varying-insize from 40micron sizeup to about 100 micron particle sizeas a fluid-becfof solid in asuspended or dispersed phase condition re-- sembling a boiling=liquid.It may'be-a dense fluid catalyst bed operation inthe range .of'3O to 40lbs/cu.ft. 'or a more dispersed catalyst phase operation generally lessthan 30 lbs/cu.ft. superimposed by an even more dispersed catalyst phasein the upper cyclone section of the regeneration Zone. I I

The present invention is concerned with the method and system forcontacting finely divided fluidizable catalyst particles comprising acrystalline zeolite with a gasiform hydrocarbon reactant material andwith regeneration gas so that the efficiency of the operation isconsiderably improved. In a more'particular aspect the invention isconcerned with a method if improving the recovery of compounds depositedon the catalyst in the hydrocarbon phase and effecting regeneration ofcatalyst particles ina swirl type dense fluid catalyst bed re--generation operation. I

In the method and system of the present invention, a crystalline zeolitehydrocarbon conversion catalyst comprising fluidizable catalystparticles and containing deactivating carbonaceous deposits due to hightemperature conversion of a gas oil boiling range hydrocarbon feed at atemperature of at least 950F. is subjected to a stripping operation bycounter-current flow to provided upflowing stripping gas. The strippinggas and stripped products of hydrocarbon conversion are re covered froma dispersed phase of catalyst above the stripping Zone by cyclonic meansbefore being passed to a hydrocarbon product separation step downstreamof the hydrocarbon conversion operation. The stripped catalyst at anelevated stripping temperature is then discharged without'coolingthereof tangentially into an adjacent catalyst regeneration zonecontaining a dense fluid bed of catalyst. The tangentially introducedcatalystimparts a swirl, circular or circumferential flow to thecatalyst particles'being subjected to contact with oxygen containing"regeneration gas under elevated temperature catalyst regenerationconditions. More particularly, thedeactivated and stripped catalystpartially desorbed of strippable contaminants in a relatively hightemperature stripping operation in the range of 900F. to I200F.. isdischarged tangentially into the regeneration zone in a section or upperportion thereof adjacent the upper interface of a fluid bed of catalyst.The stripped catalyst enters the regenerator tangentially to andpreferably into an upper fluid phase of catalyst particles above a morerelatively dense fluid bed phase of catalyst therebelow. Thus, byintroducing the catalyst tangentially into the regeneration zone andabove the most dense phase of catalyst, a circumferen tial contact ofcatalyst with regeneration gas is initiated and particularly promoted inthe swirl type of catalyst regeneration system.. Regeneration gas isintroduced by the segmented distributing grid in restricted amounts tosubstantially the entire bottom cross-sectional area of the swirling bedof catalyst for substantially vertical flow upwardly therethrough andremoval from .an upper portion of the regeneration zone after passingthrough cyclonicmeans.

In the method and system of this invention,.circulation and contact ofcatalyst with regeneration gas is accomplished by limiting the volume ofregeneration gas brought in contact with the catalyst in selectedvertical segments of the regeneration zone. Forexample, in the gridsegment F of FIG. III positioned between the catalyst inlet and catalystwithdrawl means, a most dense fluid phase of catalyst is particularlymaintained by limiting, forexample, only from 40 to of the available gasdistributor openings in the grid segment to supply tor segments A, B, Cand perhaps a portion of segment D, the available orifice openings inthe segments are 100% open for flow of regeneration gas so that apressure drop across each opening will be restricted to within the rangeof 0.4 to 1.2 psi. Thus the fluid mass of catalyst above these segmentswill be in a less dense phase condition than in the remainingcirculating bed. The catalyst bed above segments D and E will be moredense than that above A, B and C by restricting the grid openings to notmore than about The regeneration operation of the present invention isenhanced by providing a curved vertical baffle member extending fromabove the grid to a height above the catalyst tangential inlet as shownin the drawing and position with respect to the vessel wall to form anexpanding annulus representing in cross-section a conical frustrum whicheffectively channels the circumferential circulation of catalyst withinthe regenerator without generating disturbing eddy current interferingwith desired catalyst flow. Hot regenerated catalyst traversing theregenerator circumference is channeled by the an nulus for mixing withtangentially introduced contaminated catalyst thereby restrictingparticularly at the lower regeneration gas velocities the short circuitof introduced contaminated catalyst to the regenerated catalystwithdrawal well. Positioning and curvature of the baffle to provide anexpanding annulus of about 20 in the direction of catalyst flow alignedwith tangential inlet has been found suitable for preventing undesiredcirculating or eddy current about the battle and in the catalyst bed.The expanding angle of the conical annulus formed by the vertical bafflewith the regenerator wall may vary from the preferred angle of about 20by 5.

The regeneration zone is provided in its upper portion above thedensefluid bed of catalyst with a plurality of cyclonic separation meansas shown in FIG. II comprising first and second sequentially connectedcyclonic separator means for removing catalyst fines en trained with theflue gas.

In the herein described hydrocarbon conversioncatalyst regenerationarrangement, it has'been found desirable to employ a high temperaturestripping oper-' ation of at least 1050F. since such an operation willre,

tain a much larger portion of catalyst adsorbed sulfur compounds in thehydrocarbon side or phase of the operation than accomplished heretofore.Furthermore,

the higher the temperature of the catalyst mixture passed to theregeneration zone from the stripping zone in combination withtemperature adjusted regeneration gas will operate to rapidly initiatecombustion of carbonaceous deposits and thus more completely andefficiently accomplish regeneration of the catalyst particlescirculating in the swirl type regeneration zone.

It has been found in the regeneration operation of this invention thatin the direction of the catalyst circumferential swirl that the cyclonicseparating means substantially there above in any given verticalquadrant and a short distance downstream from the point of catalysttangential introduction will contain a major portion if not all of anysulfur compounds in the flue gas removed from the catalyst by oxygenregeneration. Thus in the system of this invention the first few orfirst 3 to 4 cyclonic combinations of primary and secondary connectedcyclone separation zones may be separately connected for segregated fluegas recovery of sulfur containing flue gas from the remaining flue gasesre covered in the remaining downstream combinations of cyclonicseparation means in thedir ection of catalyst swirl within theregeneration zone. In the arrangement of the system represented by FIG.II there are eight such combinations of primary and secondarysequentially connected cyclonic separation means provided in the uppercross section of the regenerator for the recovery of regeneration gasfrom entrained catalyst products. The curved vertical baffle memberabove discussed is shown extending from the dipleg of primary cyclone 8to the dipleg of the secondary cyclone of cyclonic combination 1. Thus,in the apparatus of this invention, the first 3 cyclone combinations, asshown in FIG. II, may be connected for the segregated recovery of highsulfur containing flue gases if desired. The flue gases separated may betreated to provide a total flue gas stream containing not more thanabout 200-300 ppm of S Catalyst particles traversing the swirl patternin the fluid catalyst bed also move to a lower portion of the catalystbed counter-current to upflowing regeneration gas and to a withdrawalwell positioned in the lower portion of the regeneration zone adjacentthe upper surface of the regeneration gas distributor grid. Theregenerated catalyst withdrawnby the withdrawal well at an elevatedtemperature usually in excess of about 1200F. and comprising a lowresidual coke deposit thereon is transferred by a catalyst standpipe tothe lower portion of a riser hydrocarbon conversion zone. Regeneratedcatalyst may also be passedto the catalyst stripping zone as abovesuggested thus completing the circulation of catalyst through thesystem.

It is preferred to operate the catalyst regeneration zone underconditions providing regenerated catalyst at a temperature of at leastI250F. and preferably in the range of l350 to I l-00F. for recycle asherein provided. Regeneration gas velocities are selected from withinthe range of 0.5 to about 3 or 5 ft/second, the selection being based onthat required to obtain the regeneration operation above described.

The regeneration operation above described is preferably used with oneor more riser hydrocarbon conversion zones adjacent thereto, which areprovided with a plurality of spaced apart feed inlet conduits along thelength of the riser. In this arrangement, it is contemplated introducinga low sulfur containing feed or a hydrotreated light gas oil to aninitial portion of a riser reactor and a higher sulfur containing feedor a recycle stream from the product fractionator to a downstreamportion of the riser. Furthermore, the conversion level of the higherboiling feed may be restricted as a function of its sulfur level and/orits additive coke characteristics. Thus the residence time of thehydrocarbon feeds may be altered as desired within the limits providedby the riser conversion zones. It is also contemplated using as a feedto the riser conversion zone, coker light and heavy gas oils, heavyvacuum gas oils and hydrogenated cyclic oils which give up hydrogenduring the conversion operation as well as hydrogenated virgin and cokerstocks and combinations thereof.

' BRIEF DESCRIPTION or THE DRAWINGS hydrocarbon conversion zone, acatalyst stripping zone, a fluid bed catalyst regeneration zone, andconduit means for passing regenerated catalyst to said hydrocarbonconversion zone and said stripping zone. The regenerator plenum means isshown separated to permit the separate recovery of high and low sulfurcontaining flue gas as herein described.

FIG. II diagrammatically represents a cross-sectional view of section AAof FIG. I showing the relationship existing between a plurality ofconnected cyclonic means as related to the baffle means arrangedintermediate to means for introducing and withdrawing catalyst particlesfrom the regenerator of FIG. I.

FIG. III is a cross-sectional view of the distributor grid 50 of FIG. I.

DISCUSSION OF SPECIFIC EMBODIMENTS Referring now to FIG. I, ahydrocarbon feed 2 such as a gas oil boiling from about 600F. up to1000F. is passed afier preheating thereof to the bottom portion of riser4 for admixture with hot regenerated catalyst introduced by standpipe 6provided with flow control valve 8. A suspension of catalyst inhydrocarbon vapors at a temperature of at least about 950F. but moreusually at least l0O0F. is thus formed in the lower portion of riser 4for flow upwardly therethrough under hydrocarbon conversion conditions.The suspension initially formed in the riser may be retained during flowthrough the riser for a hydrocarbon residence time in the range of l to10 seconds. Additional hydrocarbon feed material usually higher boilingthan the gas oil feed introduced by conduit 2 or one ofa higher sulfurcontent is introduced to the riser 4 atone or more spaced apartdown-stream feed injection points 10 and 12 for a hydrocarbon conversionresidence time less than that employed for converting feed introduced byconduit 2. On the other hand, the gas oil" feed may be separated so thata low boiling portion. thereof or a hydrocarbon feed fraction of lowaromatic index rating may be initially mixed with regenerated catalystin the riser and a higher boiling fraction or higher aromatic indexrated material introduced at one or more downstream feed unit points. a

The hydrocarbon vapor-catalyst suspension formed in the riser reactor ispassed-upwardly through riser 14 under hydrocarbon conversion conditionsof at least 900F. and more usually at least lO0OF. before discharge intoone or more cyclonic separation zones about the riser discharge,represented by cyclone separator 14. There may be a plurality of suchcyclone separator combinations comprising first and second cyclonicseparator means attached to or spaced apart from the riser discharge forseparating catalyst particles from hydrocarbon vapors. Separatedhydrocarbon vaors are passed from separator 14 to a plenum chamber 16for withddrawal therefrom by conduit 18. Hydrocarbon vapors and gasiformmaterial separated by stripping gas as defined below are passed byconduit 18 to fractionation equipment not shown. Catalyst separated fromhydrocarbon vapors in the cyclonic separation means is passed by diplegsrepresented by dipleg 20 to a dense fluid bed of separated catalyst 22retained about an upper portion of riser conversion zone 4.-Cat-' alystbed 22 is maintained as a downwardly moving fluid bed of catalystcounter-current to rising gasiform material. The catalyst passesdownwardly through a stripping-zone 24 immediately therebelow andcountercurrent to rising strippinggas introduced to a lower portionthereof by conduit 26. Baffles 28 are provided in. the stripping zone toimprove the stripping operation. I 1.

The stripping operation of the present invention may be improved by theaddition of hot regenerated catalyst thereto by transfer conduit 30 inan amount so that the bed of catalyst 22 provides a catalyst mixture atan elevated temperature of at least lOOOF. promoting the decompositionof compounds adsorbed on the catalyst. The catalyst is maintained instripping zone 24 for a period of time sufficient to effect a hightemperature desorption of feed deposited compounds which are thencarried overhead by the stripping gas. The stripping gas with desorbedhydrocarbons pass through one or more cyclonic separating means 32wherein entrained catalyst'fines are separated and returned to thecatalyst bed 22 by dipleg 34. The hydrocarbon conversion zone comprisingriser 4 may terminate in an upper enlarged portion of the catalystcollecting vessel with the commonly known bird cage discharge device oran open end T-connection may be fastened to the riser discharge which isnot directly connected to the cyclonic catalyst separation means. Thecyclonic separation means may be spacedapartfrom'the riser discharge sothat an initial catalyst separation is effected by a change in velocityand direction of the discharged suspensionso that vapors. lessencumbered with catalyst' fines may then pass through one or morecyclonic separation -means beforepassing to a product separation step;In any. of thesearrangements, gasiform materials comprising strippinggas hydrocarbon vapors and desorbed sulfur compounds are passed from thecyclonic separation means represented by separator 32 plenum chamber 16for removal with hydrocarbon products of the cracking operation byconduit 18. Gasiform material comprising hydrocarbon vapors is passed byconduit. 18 to a product fractionation step not shown.

Hot stripped catalyst at an elevated temperature is withdrawn from alower portion of the stripping zone by conduit 36 for transfer to afluid bed of catalyst being regenerated in a catalyst regeneration zone.Flow control valve 36 is provided in transfer conduit 36.

The catalyst regeneration operation of the present invention isreferred'to above as a swirl type of catalyst regeneration due to thefact that the catalyst bed tends to rotate or circumferentiallycirculate about the vessels vertical axis and this motion is promoted bythe operating parameter herein discussed, by the vertical curve baffleand by the tangential spent catalyst inlet to the circulating catalystbed. Thus the tangentiallyintroduced catalyst at an elevated temperatureis further mixed with hot regenerated catalyst or catalyst undergoingregeneration at an elevated temperature and is caused to move in acircular or swirl pattern about the regenerators vertical axisas it alsomoves generally downward to a catalyst withdrawalfunnel adjacent theregeneration gas distributor gridQThe catalyst withdrawal funnel ispositioned adjacent a vertical section of the regenerator vessel lyingbetween the catalyst tangential inlet and withdrawal-funnelso thatcatalyst particles introduced to the regenerator will. traversesubstantially the circumference of the regenerator vessel beforeencountering withdrawal therefrom as above described. This catalystmovement is promoted by an annular section'expanding in the direction ofcatalyst flow by about.20'and formed by a curved vertical baf- -flemember 84 spaced from the regenerator wall and adjacent the catalysttangential inlet 36. The annulus thus formed may be construed as anextension of the catalyst inlet which expands in the direction ofcatalyst flow and'operates to promote the circumferential catalystcirculation. In this catalyst regeneration environment, it has beenfound that the regeneration gases comprising flue gas products ofcarbonaceous material combustion tend to move generally verticallyupwardly through the generally horizontally moving circulating catalystto cyclone separators positioned above the bed of catalyst in any givenvertical segment. This phenomenon in cooperation with the baffleprovided and process operating conceptspermits a desired control on theregeneration operational including segregating flue gas products of highand low sulfur content when desired. Thus, asshown by FIG. ll, thecatalyst tangentially introduced to the regenerator by conduit 36 causesthe catalyst to circulate in a clock-wise direction in this specificembodiment. As the bed of of catalyst continues its circular motion somecatalyst particles move from an upper portion of the mass of catalystparticles suspended in regeneration gas downwardly therethrough to acatalyst withdrawal funnel 40 in a segment of the vessel adjacent to thecatalyst inlet segment. In the regeneration zone 42 housing a mass ofthe circulating suspended catalyst particles'44 in upflowing oxygencontaining regeneration gas introduced to the lower portion thereof byconduit distributor means 46, the density of the mass of suspendedcastalyst particles may be varied as discussed above by the volume ofregeneration gas used in any given segment or segments of thedistributor grid. Generally speaking, the circulating suspended mass ofcatalyst particles 44 undergoing regeneration with oxygen containing gasto remove carbonaceous deposits by burning will be retained as asuspended mass of swirling catalyst particles varying in density in thedirection of catalyst flowdue to plugging of the grid as above discussedand a much less dense phase of suspended catalyst particles 48 willexist thereabove to an upper portion of the regeneration Zone. Undercarefully selected relatively lowregeneration gas velocity conditions, arather distinct line of demarcation may be made to exist between a densefluid bed of suspended catalyst particles and a more dispersed suspendedphase of catalyst thereabove. However, as the regeneration gas velocityconditions are increased there is less of a demarcation line and thesuspended catalyst passes through regions of catalyst particle densitygenerally less than about 30 lbs. per cu.ft. A lower catalyst beddensity of at least 20 lb/cu.ft. is preferred. 8 I

A segmented regeneration gas distributor grid 50 positioned in the lowercross-sectional area of the regeneration vessel 42 is provided as shownin FIGS. l and Ill and is adapted to control -the'flow of regeneration.

gas passed to any given vertical segment of the catalyst bed thereabove.In this arrangement, it has been found that even with the generallyhorizontally circulating of catalyst, the flow of regeneration gas isgenerally vertically upwardly through the mass of catalyst particles sothat regeneration gas introduced to the catalyst bed by any given gridsegment or portion thereof may be controlled by grid openings madeavailable and the air flow rate thereto as discussed above. Thus, oxygencontaining combustion gases after contact with catalyst in theregeneration zone are separated from entrained catalyst particles by thecyclonic means provided and vertically spaced thereabove. The cyclonecombinations diagrammatically represented in FIG. I are intended tocorrespond to that represented in FIG. II. Catalyst particles separatedfrom the flue gases passing through the cyclones are returned to themass of catalyst therebelow by the plurality of provided catalystdiplegs.

As mentioned above, regenerated catalyst withdrawn by funnel 40 isconveyed by standpipe 6 to the hydrocarbon conversion riser 4. Withdrawnregenerated catalyst is also conveyed by conduit 68 provided with flowcontrol valve 70 to a riser transfer conduit 72 for transferring hotregenerated catalyst to the stripping step above described.Substantially any suitable gasiform material introduced by conduit 74 tothe lower portion of riser 72 may be used for this purpose.

In the catalyst regeneration system of the present invention, it iscontemplated employing a total catalyst recycle through the cyclonediplegs to the catalyst bed in the range of l to 2 volumes per volume ofcatalyst introduced from the stripping zone and a higher rate ofcatalyst circulation through one or more of the combinations of catalystdiplegs than the other diplegs is contemplated. For example, a higherrate of catalyst circulation may be imposed upon the cyclone system ofcyclones 1, 2 and 3 than on the remaining cyclonic systems.

In the arrangement of FIG. lll, there is shown a segmented regenerationgas distributor grid 50 comprising regeneration gas distributing pipes80 connected to main supply conduits 82 herein referred to as radiatingsupply conduits A, B, C, D, E and F connected to concentric regenerationgas inlet conduit 46 which is closed at its upper end positioned withinthe lower or bottom portion of vessel 42. Catalyst withdrawal funnel 40connected to conduit 6 is shown positioned between two of the segmenteddistributing grids E and F. The dotted conduit 36 at the side of thedrawing is intended to show the relationship of the catalyst tangentialinlet conduit 36 to the withdrawal funnel 40.

Having thus provided a discussion of the apparatus and system of thepresent invention and described the method for using the apparatus, itis to be understood that no undue restrictions are to be imposed byreason thereof except as defined by the following claims.

We claim: 1. In a hydrocarbon conversion-catalyst regeneration operationin the presence of fluidizable catalyst particles, the improved methodof regenerating the catalyst which comprises,

maintaining a dense fluid bed of catalyst particles circulatingcircumferentially in a catalyst regeneration zone,

introducing catalyst particles obtained from a hydrocarbon conversionoperation after stripping thereof into saidregeneration zonetangentially to said circulating bed of catalyst in a restricted annularsection expanding in the direction of catalyst circulation, said annularsection formed by a curved upwardly extending baffle spaced inwardlyfrom the outer wall of the regeneration zone,

passing regeneration gas upwardly through said circulating fluidbed ofcatalyst in said regeneration zone,

recovering gaseous products of regeneration from an upper portion of theregeneration zone, and withdrawing regenerated catalyst from a lowersection of said fluid bed of catalyst upstream said tangentiallyintroduced catalyst to said circulating bed and outside of saidrestricted annular section.

2. The method of claim 1 wherein the restricted an nular section isformed by a curved baffle member spaced apart from the regenerator wallin a manner to form the expanding annular section and said annularsection expands at an angle of about 20 5v 3. The method of claim 1wherien the volume of regeneration gas passed upwardly through saidcirculating bed of catalyst is highest at the catalyst inlet anddownstream thereof for a portion of its circumferential flow and islowest in the region of regenerated catalyst withdrawal from the fluidbed of catalyst.

4. The method of claim 1 wherein the density of the circumferentiallycirculating fluid bed of catalyst in the regeneration zone is lowest inan initial portion of the circulating catalyst flow pattern and highestnear the catalyst withdrawal.

1. IN A HYDROCARBON CONVERSION-CATALYST REGENERATION OPERATION IN THEPRESENCE OF FLUIDIZABLE CATALYST PARTICLES, THE IMPROVED METHOD OFREGENERATING THE CATALYST WHICH COMPRISES, MAINTAINING A DENSE FLUID BEDOF CATALYST PARTICLES CIRCULATING CIRCUMFERENTIALLY IN A CATALYSTREGENERATION ZONE, INTRODUCING CATALYST PARTICLES OBTAINED FROM AHYDROCARBON CONVERSION OPERATION AFTER STRIPPING THEREOF INTO SAIDREGENERATION ZONE TANGENTIALLY TO SAID CIRCULATING BED OF CATALYST IN ARESTRICTED ANNULAR SECTION EXPANDING IN THE DIRECTION OF CATALYSTCIRCULATION, SAID ANNULAR SECTION FORMED BY A CURVED UPWARDLY EXTENDINGBAFFLE SPACED INWARDLY FROM THE OUTER WALL OF THE REGENERATION ZONE,PASSING REGNERATION GAS UPWARDLY THROUGH SAID CIRCULATING FLUID BED OFCATALYST IN SAID REGENERATION ZONE RECOVERING GASEOUS PRODUCTS OFREGENERATION FROM AN UPPER PORTION OF THE REGENERATION ZONE, ANDWITHDRAWING REGENERATED CATALYST FROM A LOWER SECTION OF SAID FLUID BEDOF CATALYST UPSTREAM SAID TANGENTIALLY INTRODUCED CATALYST TO SAIDCIRCULATING BED AND OUTSIDE OF SAID RESTRICTED ANNULAR SECTION.
 2. Themethod of claim 1 wherein the restricted annular section is formed by acurved baffle member spaced apart from the regenerator wall in a mannerto form the expanding annular section and said annular section expandsat an angle of about 20* + or -
 5. 3. THE METHOD OF CLAIM 1 WHEREIN THEVOLUME OF REGENERATION GAS PASSED UPWARDLY THROUGH SAID CIRCULATING BEDOF CATALYST IS HIGHEST AT THE CATALYST INLET AND DOWNSTREAM THEREOF FORA PORTION OF ITS CIRCUMFERENTIAL FLOW AND IS LOWEST IN THE REGION OFREGENERATED CATALYST WITHDRAWAL FROM THE FLUID BED OF CATALYST.
 4. THEMETHOD OF CLAIM 1 WHEREIN THE DENSITY OF THE CIRCUMFERENTIALLYCIRCULATING FLUID BED OF CATALYST IN THE REGENERATIO N ZONE IS LOWEST INAN INITIAL PORTION OF THE CIRCULATING CATALYST FLOW PATTERN AND HIGHESTNEAR THE CATALYST WITHDRAWAL.